Building construction and method



Aug. 27, 1968 H. N. BABCOCK BUILDING CONSTRUCTION AND METHOD 2 Sheet 1Filed May 13' 5 VEN Henry N, gubcock ATTORNEYS Aug. 27, 1968 H. N.BABCOCK BUILDING CONSTRUCTION AND METHOD 2 Sheets-Sheet 2 Filed May 13,1965 Hvw/ u h I I I I l LEEUI I IH H FIG. 7

INVENTOR Henry N. Bobcock BY f ATTCIDFZ? United States Patent TBUILDINGCONSTRUCTION AND METHOD Henry N. Babcock, 4 Quintard Ave., OldGreenwich, Conn. 06870 Filed May 13, 1965, Ser. No. 455,429 17 Claims.(Cl. 52-90) ABSTRACT OF THE DISCLOSURE The present invention relates toa structural building system and more particularly to a building systememploying flat sheet metal for enclosing a frame structure where thestrength characteristics of the metal sheets are utilized by tensioningthe sheets after they are placed over the frame structure so as todevelop a predetermined integral strength in the entire structure thatis sufficient to withstand predetermined variable loads to which thebuilding, and in particular the covering, will be subjected.

For many types of building constructions, it is conventional to form theroof and or sides of the building of corrugated or ribbed metal panelsthat are pre-fabricated from rolled sheets. Where pre-fabricatedcorrugated panels are employed in covering building structures, they areusually supported on purlins that are commonly made of metal. Thussupported, they operate similar to beams resting over one or morepurlins. There is, however, no structural continuity from one sheet toanother as they pass over the roof of a building. Each sheet operatesindependently of the other, each is fastened by itself and there is notransfer of load or attachment from sheet to sheet. Also, in coverin abuilding with corrugated metal sheets, certain minimum strengthcharacteristics must be maintained. For example, the metal covering mustbe capable of withstanding the various dead and live loads to which itwill be subjected, and the sheets must be capable of remaining taut onthe building framework regardless of temperature changes in the ambientatmosphere that will tend to cause the sheets to expand.

Overall tautness of the building covering is important to the extentthat loosenness of the covering will permit the sheets to deflect andvibrate under varying load conditions and thus subject the entirebuilding to forces that tend toweaken its strength. Load requirements ofbuildings covered with corrugated sheets are met primarily by thestrength of the underlying framework and by the gauge of metal used informing the corrugated sheets. In addition, the corrugations that arepre-formed in the sheet give the individual sheets the strength requiredto withstand expected loads that will be encountered between thesupporting portions of the framework. To maintain the required tautnessin the sheets, they are normally rigidly attached to the framework atspaced intervals with the spacing between the points of attachment madesmall enough so that any expansion of the sheets that might be caused bychanges in the temperature of the ambient atmosphere will be limited inextent.

Although building constructions employing corrugated sheets have found awidespread use, they do possess certain cost and strength disadvantages.To begin with, the pre-fabrication of these metal panels to produce thecorrugations reduces the coverin or usable area of the sheets. A flatsheet sixty inches in width, for example,

"ice

will, after being corrugated, have an efiective width of only thirty-sixinches. Not only does this pre-fabrication reduce the covering area ofthe metal sheet, but, in addition, by requiring a separate manufacturingoperation, it increases the cost of the sheet as supplied to the user.Also, the inherent structural tensile strength of the metal is not usedto amaximurn due to the formed corrugations.

In accordance with the teachings of the present invention, thedisadvantages of pre-fabricated corrugated sheet coverings are avoidedby using flat sheet metal panels and by tensioning these panels over thevarious load bearing beams that form the buildings frame structure.Panels stressed over the load bearing beams in this manner provide aunique structural system. The stressed sheet, when anchored on one sideof a building, stretched up the side walls, over the roof and down theother side and then tensioned, enhances the integral strength of thestructure, provides greater bearing strength for the roof and deckloadings and reduces the quantity of structural materials required tosupport such a cover. In addition, such a construction reduces the costand time of installation of the building enclosures, eliminates most ofthe fabricating procedures usually required in such a structure, reducesthe dead weight design requirements of the covering system and providesa structure which is basically stronger and has a longer life.

For maintaining the sheets relatively taut between the adjacentsupporting beams over which they are stretched, the amount of inducedtension or stress created in each sheet may be made sufiiciently greatto efiectively compensate for the normal expansion of the sheet thatwill be caused by ambient temperature variations encountered in thelocation where the building is erected. In other words, each sheet maybe stressed by a predetermined amount such that when the sheetsubsequently expands as the ambient temperature increases, the stressthen remaining in each sheet will still be adequate to maintain asufiicient degree of tautness for effectively resisting thepredetermined loads to which the covering will be subjected.

The sheets that are used in carrying out the teachings of the presentinvention may vary in width depending on what the various mills arerolling and what best fits the particular project. Sheets are presentlyavailable up to 72 inches without special order, and with a 72 inchsheet, a roof covering area of approximately 66 inches per sheet wouldbe produced. If the normal corrugated metal sheet were used insuccession, the coverage would be approximately 60% less per sheet dueto the necessary rib or fluting required.

When a building has the tensioned or stressed cover of the presentinvention, the requirements for such things as cap flashing and ridgeflashing are eliminated. In addition, the number of joints in such abuilding as compared to one using corrugated sheets is reduced by over60%. Also, the gauge of metal required as compared to a normalcorrugated sheet is reduced by a considerable amount as well as is thenumber of supporting purlins required. Other advantages obtained withthe present invention are the reduction of the poundage of structuralsteel required to support such a building and the amount of foundationsrequired to support such as structural system.

There will be little possibility of vibration of the metal sheet due towind loads both positive and negative. Because of the strength affordedby the system of the present invention, lighter, faster, and cheaperconstructions become possible; and where the sheets are made ofstainless steel, a construction requiring little if any maintenance isproduced.

A more complete understanding of the present inven- 3 tion includingboth the structural details and the method of construction will beobtained from the following description with reference being made to theaccompanying drawings of which:

FIG. 1 is a perspective view of one embodiment of a building constructedin accordance with the teachings of the present invention;

FIG. 2 is a detailed blowup of the encircled portion designated A inFIG. 1;

FIG. 3 is a detailed blowup of the encircled portion designated B in inFIG. 1;

FIG. 4 is a detailed blowup of the encircled portion designated C inFIG. 1;

FIG. 5 is a detailed blowup of the encircled portion designated D inFIG. 1;

FIG. 6 is a perspective view of one of the wedge shaped shims shown inFIG. 5;

FIG. 7 is a schematic end view of a modified embodiment of the presentinvention; and

FIG. 8 is a schematic view of still another embodiment of the presentinvention.

As shown in FIG. 1, the building system of the present inventiongenerally includes a foundation 1 comprised of concrete footings 2 andconcrete piers 3. The foundations are provided in the form of elongatedmembers which extend parallel with all load bearing members or beamsindicated generally at 4. These beams are in turn supported byvertically disposed posts or columns 5 by suitable means such as weldingor attaching plates, not shown. Each of the load supporting beamsconsists of a web 6, an upper flange 7, and a lower flange 8 with theedges of the upper flange beveled or rounded as more fully describedbelow.

Once the foundations have been laid and the posts and supporting beamsconnected in place, the resulting frame- Work is ready to receive acovering. According to one embodiment of the present invention as shownin FIG. 1, the covering comprises a plurality of elongated flexiblemetal sheets 9 such as stainless steel sheets that are placed over thesupporting beams 4 in overlapping relationship with each other andsecured to the foundations so as to provide both the roof and wallportions of the building. The sheets used in the building system of thepresent invention are flat in nature as opposed to corrugated sheets andmay be of any desired width depending on the particular project beingconstructed. For example, rolled sheets 72 inches in width may be usedand placed in overlapping relationship with an overlap at eachlongitudinal edge of three inches so as to provide an eflective coveringarea of about 66 inches for each sheet.

The covering of the building starts at one end 11 with a first sheet 9'which may be unrolled from a supply roll fed up one side 12 of thebuilding, over the roof 13, and down the other side 14. The sheet isthen cut from the supply roll and the opposite ends 15, 16 anchored onthe piers 3 against movement with respect to the load bearing beams 4 asby means of anchor angles 17. Since this first sheet has a portion thatis stretched down the side of the end columns 5, an anchor angle will beused for the remaining portion of the sheet adjacent the columns and theportions of the sheet in alignment with the columns may be secureddirectly to the side of the piers 3 as shown in FIG. 1. It will be notedfrom FIG. 2 that the heel of the anchor angle is rounded to preventcutting or creasing of the sheet at this point. Similarly, it will benoted that the appropriate edges of the load bearing beams 4 are alsorounded where they engage the sheet metal.

After the first sheet 9' is anchored to the piers, a second sheet 9" iserected in a similar fashion with several inches of overlap beingprovided with respect to the first sheet 9. At the point of overlap, aweathertight gasket, such as a butyl rubber bead 18, is installed. Thisprocedure is repeated with succeeding sheets down the length of thebuilding until the opposite end 19 is reached.

After the building is completely covered with the re quired number ofsheets tightened and anchored to the piers 3, the center posts ofcolumns 5' are raised a pmdetermined number of inches or fractionsthereof to tension the sheets longitudinally. For the purpose of raisingthe columns 5, wedge shaped shiins 20, such as disclosed in my UnitedStates Patent 2,943,716,. are -employed. These shims are insertedbetween column base plates 21 attached to each of the columns 5' andfoundation base plates 22 attached to the piers 3 as shown in FIG. 5.The shims are then driven between these two plates, raising the columnsthe proper amount to, in turn, tension the individual sheets therequired amount. As the sheets are tensioned, they will compress theintermediate gaskets 18 to effect a watertight seal between the sheets.

The amount of tension induced in the sheets will depend on the loads towhich the building will be subjected during use and this will in turndepend on the geographical location of the building. Of importance indetermining the amount of tension necessary to withstand the loads isthe temperature variations that will be encountered where the buildingis erected. The sheets used in covering the building have thecharacteristics of contracting and expanding as the temperature of theambient atmosphere changes. The higher the temperature, the more thesheets will expand and as the sheets expand they tend to become loosebetween the adjacent supporting beams 4. As such they are subject todeflection and vibration that would tend to be caused by wind loads, forexample. In addition, loose sheets are less capable than tensionedsheets of withstanding load conditions produced, for example, byaccumulated snow.

According to the teachings of the present invention, the sheets aretensioned to a stress value suflicient to enable them to resist anyappreciable deflection and to withstand the variable loads to which theywill be subjected as they expand and contract with temperaturevariations in the ambient atmosphere. To calculate the tension stressforthe sheets of a building to be constructed in any given location, themaximum loads including, for example, live,'

dead, and wind loads to which the building will be subjected are firstdetermined. To these maximum values a safety factor may be added ifdesired or required by local building codes. Next, the temperature rangefor that location is found and from this, the maximum amount of sheetexpansion calculated. These values are then correlated with thepreviously tested loads which the sheets are capable of withstandingunder various degrees of tensions; and the sheets are then tensioned toa stress value which will be suflicient to resist these loads under theassumed range of temperatures.

Usually, if the sheets are tensioned an amount sufficient to compensatefor temperature expansion so that when the sheets are fully expandedthey will have enough tension to resist deflection and vibration and towithstand the loads that will be encountered at this temperature, thisvalue of tension will be more than enough to enable the sheets towithstand the loads encountered at other temperatures. Accordingly, inmost situations, the sheets need not be tensioned to completely preventdeflection as they expand, the important criteria to be considered beingthe amount of loading to which the building will be subjected inrelation to the expected temperature of the ambient atmosphere at thetime of such loading. Most often, the higher loads to which the buildingand covering will be subjected will occur with lower temperatures. Atthese temperatures, however, the sheets are normally in a morecontracted state and thus inherently more able to withstand high loadseven though the amount of induced tension at the maximum temperature isless than that required to prevent deflection. For example, one type ofloading to which the building and covering will be subjected is thatcreated by the accumulation of snow on the roof. This type of loading,however, will occur at low temperature values under which conditions thesheets will have contracted to increase their induced tension and thesheets will therefore be in a state most capable of withstanding suchsnow loads; In addition, wind loads which are usually accompanied bystorms with-resulting temperature decreaes, are similarly counteractedby the sheets contracting with the falling temperature. Thus, it will'be seen that the building system of the present invention actuallytakes advantage of the changing conditions of nature to strengthen thebuilding at the time such additional strength is needed to withstand theloads to which it will be subjected. Of course, in any unusualsituation, as-for example, when the loads will be a maximum at thehigher temperatures, this will be taken into account in originallytensioning the sheets.

Instead of tensioning all of the sheets at one time as describedabove,they may be tensioned successively after they are placed over theadjacent portions of the load bearing members and before the nextsucceeding sheet is erectedFor-example, where a number-of verticallyadjustable columns 5' are provided down the length of the building, andmost advantageously where one of such columns is positioned directlybeneath each sheet of covering, the column disposed below a particularsheet maybe raised immediately after the corresponding sheet has beenerected. Where this procedure is followed, the original tension appliedto each succeeding sheet may be made less by progressively decreasingamounts than the desired final tension so that when the last column israised the required amount, it will in turn finally increase the tensionof all the sheets by the last increment necessary to" produce thedesired overall results.

Also, the tension in adjacent sheets need not necessarily be equal toeach other as long as the tension of each sheet is at least of a minimumvalue that will enable that sheet to withstand the required loads.Accordingly, where the vertical columns are to be raised successivelyafter the succeeding sheets are erected, the raising of each succeedingcolumn down the length of the building need only be of such an amount toassure the creation of this minimum value without particular'regard tothe increased tension induced in the preceding sheets as the erectingand tensioning operation progresses from one end of the building to theother.

In another embodiment of the present invention as shown in FIG. 7,stationary columns 23 are employed and each sheet 9 is tensionedindividually after it is erected over the load bearing beams 4. As withthe embodiment of the invention shown in FIG. 1, the sheets are appliedin overlapping relation. Here, however, each sheet is'cut after erectionand the free ends 15, 16 are attached through suitable stress gauges 24to tensioning lines 25 which are in turn connected to a power winch 25.By actuating the power winch in the clockwise direction as viewed inFIG. 7, the sheet 9 is tensioned over the load bearing beams 4 and suchtensioning is continued until the gauges 24 show the desired value.Next, the tensioned sheet is anchored at its endsby the anchor angles 17and the tensioning device disconnected. After the first sheetis properlytensioned and anchored, the succeeding sheets are then successivelyerected in a similar fashion with the desired overlap and sealing gasketbeing provided until the entire length of the building is covered;'

In a variation of this last described embodiment of the presentinvention, the tensioning device and which may be eliminated and therequired tension produced in each sheet by deflecting the trailing endof the sheet before it is cut from its supply. As shown in FIG. 8, atruck 26 having two suppliesand 10' of sheet :metal is provided, thesupply'roll 10 being positioned on a vertically adjustable support 27.This truck may be used to deliver the sheet metal directly from the millwhere it is rolled to .the particular'project being constructed. Toerect any one sheet over the load bearing beams 4 of the building, thetruck isbrought into the position shown' in'FIG. 8 and the sheetunrolled from the'supply roll-10; fed -un der the elevated supply roll10'-, passed-'overthe load bearing beams 4 and anchored 'atitsleadingendmane foundation 1 on the right side of the building as viewed in FIG.8.To induce the required tension into this sheet, the supply roll 10 isthen fixed against rotation and the supply roll '10', which is mountedon the vertically adjustable support 27, lowered onto the sheet 9passing" thereunder. This sheet will accordingly be deflected and"thereby induce a tension in a direction along the length of the -sheet,the required amount of tension being provided by" con trolling theextent to which the supply roll 10' is lowered. After the first supplyroll has been exhausted, tensioning of the sheets fed from supplyroll-10- may then be effected by means of the tensioning device shownin' FIG. 7. Alternatively, the supply roll 10' may be moved to theposition originally occupied by "the supply" roll 10 and a-suitableweight placed on the adjustable'support 27 for creating the requiredtension."

Where it is desired to reduce the stress required in the metal sheetsdue to temperature changes, this may be done by applying a thermalinsulating material to one or both sides of each sheet before it istensioned. For example, an insulating material such as urethane foamwhich is self-bonding, can be sprayed to the top side and and/orunderside of the metal sheet in the manner described in my copendingpatent application No. 349,669 entitled Structural Systems EmployingFoaming-In- Place. As such, the metal sheet is considerably insulatedfrom temperature changes, and when, for a temperature change ofuninsulated sheets would normally be stressed for a temperature changeof about if a safety factor of 30 is to be included, the addition of insulation of one inch urethane on the top side and /2 inch on theunderside, will produce a sheet such that a 100 temperature differentialwill only produce a direct temperature differential on the sheets of 15.Thus with this insulation system, the sheets will only have to bestressed for a temperature differential of about 20'to 25. With theinstallation of rigid foam on both sides of this system, a strongersheet is also obtained because of the trength of the bond and with theinstallation of a sprayedin-place fireproof foam insulating material,the cheapest possible fireproof or fire resistant structure isavailable. A variation of the above-described "procedures can be usedfor roof covering only. In such 'a situation, the sheets will beattached to opposite eaves of the building and then the mediansupporting columns shimmed up the required distances to stressthe'sheetproperly. Inthis case, the exterior columns will remain stationary;Tensioning of the sheets in this situation can also be effected bywedging beam connections in the roof system, if such is found desirableor by using" stationary columns and tensioning the individual sheetsafter they are applied in a manner similar to that described with'reference to FIG. 7.

Where openings are required in a roof system or wall system, they can becut in at a later date as the sheet is erected and stressed as long asthe openings leave en'ough' cross-sectional areas of the covering sheetto provide-the required tension. If the opening is too large for theremaining parts of the sheet to carry the required tension, a reinforcedsheet can be attached to the existing tensioned sheet to increase therequired cross-sectional area for cut out purposes or a thickertensioned sheet can be used at this point.

Also, it is not essential that the sheets be stressed over the width ofa structure. They may be stressed in the opposite direction by layingthe firt sheet at the eaves and overlapping each sheet thereafter untilthe ridge of the roof is passed and by then progressing down the otherside of the roof.

7 The system of the present invention has an added advantage in that itmay be erected in almost any weather because the workman does not haveto walk on'steel. Also, there are less joints for possible leakage. Withsprayed insulation, heat losses are reduced to a minimum and withsprayed urethane foam, corrosion is eliminated on these sheets.Expansion provisions do not have to be taken care of in the length ofthe sheet other than by stressing the sheets longitudinally; and in thewidth of the sheet, expansion can take-place over the flexible sealantsuch as butyl. Thus,emany of the normal building expansion joints areeliminated. When the roof or wall system receives a temperaturedifferential, reducing the induced tension in the sheet, the supportingstructural system will also have an induced expansion which will tend tocounteract the tension reduction in the sheet due to the temperaturediiferential.

The system of ,the present invention can be installed on a flat orsloping roof. It will have a vapor transmission rate of zero, and if astainless steel sheet is used, will have an exceedingly long lifeexpectancy.

If a steel sheet is used with urethane insulation on the top and bottomsides, a protective coating of paint for corrosion purposes will not berequired. The urethane foam on the outer surface can have a compressivestrength of from 20 p.s.i. to over 3000, whatever is required. Theoutside of the metal deck or the foam can be painted or coated with allpresently known materials, if so desired. The installation of a foam onthe underside will provide a considerable acoustical value in additionto its corrosive protection, insulation protection, fire protection, andstructural value.

Although the above description of the present invention has been madewith reference to certain preferred embodiments, it is to be understoodthat the teachings of the invention are equally applicable to erectingother types of building constructions that are to be covered with sheetmetal, as for example storage tanks, and that various other changes canbe made without departing from the scope of the invention as set forthin the following claims.

I claim: 1. In a self-supporting building construction, the combinationcomprising:

(a) a set of spaced load bearing members; and (b) at least one sheet offlat metal capable of contracting and expanding with temperaturevariations to alter any tension induced therein, each of said sheetsbeing slidably supported solely by said members and extendingtransversely thereacross with the ends of each sheet disposed onopposite sides of said set of members being anchored against movement toplace each sheet under an induced permanent tension applied thereto in adirection extending transversely of said members, said tension being ofa value sufficient to enable each of said sheets to resist deflectionintermediate said members as said sheet expands and contractstransversely of said members due to temperature variations in theambient atmosphere. 2. In a self-supporting building constructionadapted to withstand predetermined variable loads, the combinationcomprising:

(a) a set of spaced load bearing members defining a framework for saidbuilding; and

(b) at least one continuous sheet of fiat metal capable of contractingand expanding with temperature changes slidably supported solely by saidload bearing members and extending along a predetermined pathtransversely across said load bearing members, said sheet having itsends disposed on opposite sides of said set of load bearing membersanchored against movement to induce a predetermined permanent tension insaid sheet along said path so that as said sheet contracts along saidpredetermined path due to temperature decreases, said tension willincrease to'in turn' increase the load bearing capabilitie's' of saidsheet. 3. In a self-supporting building constructioniadapted'towithstand predetermined yariable loads, the combination comprising:

(a) a set of parallel spaced load bearing beams;

(b) a plurality of elongated flat flexible metal sheets capable ofcontracting and expanding with temperature variations to alter anytensioninduced therein,

, said sheets being supported by saidbeams and ex- I tendingtransversely therea'crossj'with longitudinal edges of adjacent sheetsoverlapping eachiother' in shingle-likt'e'formation, the endsof eachsheet b'eing anchored against movement on opposite sides of said set ofbeams to place each of said sheets under a predetermined induced andpermanent tension applied in a direction extending along its length,said predetermined induced tension being of a value sufficient to enablesaid sheets to withstand said predetermined loads as temperaturevariations in the ambient atmosphere cause said sheets to expand andcontract longitudinally; and

(c) a sealing gasket disposed between the adjacent overlapped edges ofsaid sheets and extending the length thereof.

4. In a building construction as set forth in claim 3 wherein:

(a) said sealing gasket is of compressible material held in compressionbetween said sheets.

5. In a building construction as set forth in claim 3 wherein:

(a) each of said sheets is coated with a layer of thermal insulatingmaterial.

6. In a building construction as set forth in claim 5 wherein:

(a) said insulating material is self-bonding foam and is aflixed to bothsides of said sheets.

7. The method of constructing a building adapted to withstandpredetermined variable loads comprising the steps of:

(a) erecting a plurality of parallel rows of vertical columns with thecolumns of each row being in spaced relation;

(b) supporting a load bearing member on each row of columns;

(c) covering said load bearing members with at least one section of flatmetal sheet capable of contracting and expanding with temperaturevariations with opposite ends of said sheet disposed on opposite sidesof said set of load bearing members;

(d) permanently tensioning said sheet in a direction transversely ofsaid load bearing members to a value sufiicient to enable said sheet towithstand said predetermined loads as it expands and contracts in adirection transversely of said load bearing members due to temperaturevariations in the ambient atmosphere; and

(e) anchoring the ends of said sheet against movement with respect tosaid load bearing members.

8. The method of constructing a building as set forth in claim 7wherein:

(a) the opposite ends of said sheet are anchored against movement withrespect to said load bearing members before said tension is applied.

9. The method of constructing a building as set forth in claim 7wherein:

(a) the opposite ends of said sheet are anchored against movement withrespect to said load bearing members after said tension has beenapplied.

10. The method of constructing a building as set forth in claim 7wherein:

(a) one end of said sheet is anchored against movement with respect tosaid load bearing members before said tension is applied; and

(b) the opposite end is so anchored after said tension has been applied.

11. The method of constructing a building as set forth in claim 7wherein:

(a) a plurality of said sheets are placed over said load bearing memberswith the edges of adjacent sheets extending transversely of said loadsupporting members overlapping each other in shingle-like formation.

12. The method of constructing a building as set forth in claim 11further including the step of:

(a) positioning a compressible sealing gasket between the overlappededges of each sheet.

13. The method of constructing a building according to claim 12 wherein:

(a) the tension is applied to each sheet individually before the tensionis applied to the next adjacent overlapping sheet.

14. The method of constructing a building according to claim 12 furtherincluding the step of:

(a) covering at least one side of each sheet with a thermal insulatingmaterial.

15. The method of constructing a building adapted to Withstandpredetermined variable loads comprising the steps of:

(a) erecting a plurality of parallel rows of vertical columns with thecolumns of each row being in spaced relation and with the columns of atleast one row being adjustable in height;

(h) supporting a load bearing beam on each row of columns;

() covering a first portion of said load bearing beams with a firstelongated sheet of fiat flexible metal capable of contracting andexpanding along its length with temperature variations, said first sheetextending in a direction transversely of said load bearing beams withthe ends thereof disposed on the opposite sides thereof;

(d) anchoring the ends of said first sheet against movement with respectto said load bearing beams;

(e) successively covering succeeding adjacent portions of said loadbearing beams with additional elongated sheets of said flat flexiblemetal with each successive sheet overlapping the next preceding sheet inshinglelike formation;

(f) anchoring the ends of each successively applied sheet againstmovement with respect to said load bearing beams; and

(g) increasing the height of the adjustable columns to tension all ofsaid sheets in a direction along their lengths to a value sufiicient toenable said sheets to withstand said predetermined loads as they expandand contract in a direction along their lengths due to temperaturevariations in the ambient atmosphere.

16. The method of constructing a building as set forth in claim 15further including the step of:

(a) positioning a compressible sealing gasket between the overlappededges of each sheet.

17. The method of constructing a building adapted to withstandpredetermined variable loads comprising the steps of:

(a) erecting a plurality of parallel rows of vertical columns with thecolumns of each row being in spaced relation;

(b) supporting a load bearing beam on each row of columns;

(c) covering a first portion of said load bearing beams with a firstelongated sheet of flat flexible metal capable of contracting andexpanding along its length with temperature variations, said first sheetextending in a direction transversely of said load bearing beams withthe ends thereof disposed on the opposite sides thereof;

(d) permanently tensioning said first sheet in a direction transverselyof said load bearing beams to a value sulficient to enable said firstsheet to withstand said predetermined loads as it expands and contractsin a direction transversely of said load bearing beams due totemperature variations in the ambient atmosphere;

(e) anchoring the opposite ends of said first sheet against movementwith respect to said load bearing beams;

(t) covering succeeding adjacent portions of said load bearing beamswith succeeding sheets of said flat flexible metal overlapping the nextpreceding sheet in shingle-like formation with a compressible sealinggasket disposed between the overlapped edges of adjacent sheets; and

(g) successively permanently tensioning and anchoring each overlappingsheet in the manner of said first sheet and before the next followingoverlapping sheet is so tensioned and anchored.

References Cited UNITED STATES PATENTS 2,427,021 9/1947 Rapp 522222,827,138 3/1958 Roy a- 52222 X 2,943,716 7/1960 Babcock 52122 X2,988,810 6/1961 Wilken 52222 X 3,057,119 10/ 1962 Kessler 52222 X3,113,403 12/1963 MacMillan 5263 X 3,277,219 10/1966 Turner 52309 X3,295,267 1/1967 Lundell 52222 X 2,382,357 8/1945 Watter 52222 FRANK L.ABBOTT, Primary Examiner.

P. C. PAW, Assistant Examiner.

